Cigarette filters employing sugar esters



3,443,566 CIGARETTE FILTERS EMPLOYING SUGAR ESTERS Yoshifumi Yasuda, Saijo, Japan, assignor to Kurashiki Rayon Co., Ltd., Sakazu, Kurashiki, Japan N Drawing. Filed July 29, 1965, Ser. No. 475,894 Claims priority, application Japan, Aug. 3, 1964, 39/ 43,496; Sept. 2, 1964, 39/ 49,866 Int. Cl. A24f 7/04 U5. Cl. 131267 7 Claims ABSTRACT OF THE DISCLOSURE A cigarette filter manufactured by adhering sugar esters on filter consisting of cellulose material selected from viscose rayon fiber and paper in an amount of 0.05 to 10% by weight based on the weight of said filter by spraying or dipping and molding the resulting filter into a cylindrical shape.

This invention relates to cigarette filters wherein sugar ester is applied to filter elements.

In order to lessen the ill effects of smoking on human health by filtering 01f the noxious and irritative substances from tobacco smoke; cigarette filters have been developed and numerous contrivances and proposals have hitherto been made for improvements of the filters. However, the only cigarette filter which has thus far been put in commercial production with filtration properties satisfactory to some extent, is formed of cellulose acetate fibers used as the filter elements with a plasticizer or a solvent added thereto for surface bonds of the cellulose acetate filaments.

According to the present invention, viscose rayon fiber or paper is used as the filter elements of cigarette filters. Viscose rayon fibers are more advantageously available commercially and possess no less adequate combined filtering properties for tobacco smoke than cellulose acetate fibers. Nevertheless, in forming cigarette filters of viscose rayon fibers there are many technical difiiculties, and the fibers have ununiform filterability for each of the smoke components, and thus a viscose rayon filter affects the balance of the smoke constituents and impairs the taste and flavor of tobacco. Attempts have been made to use paper as cigarette filter elements. Paper has advantages in that it can be formed into filters with ease and at low cost, but the cigarette filter using paper as filtering element has inevitable drawbacks in that it gives irritative taste and lacks the harmony of taste.

The present invention successfully overcame the foregoing difficulties, nevertheless whether the filter elements to be employed is viscose rayon fibers or paper, which will be hereinafter called merely as cellulose materials.

The cigarette filters according to the invention are composed of filter elements of cellulose carrier materials added with sugar esters in an amount of 0.05 to 10% by weight based on the weight of the filter elements, and formed together to a cylindrical shape. It is not yet clear at the present stage of study which constituents of tobacco smoke is removed more selectively by the cigarette filters formed of cellulose materials containing a sugar ester, or by what mechanism the former cigarette filter according to the invention maintain the balance of smoke constituents if compared with the cigarette filters formed by cellulose materials only. In fact, however, the cigarette filter according to the invention, when fitted to a cigarette and tested, it gives a much more moderate and balanced taste than the ordinary cigarette equipped with filters of cellulose materials only.

nited States Patent 0 ice The term sugar ester used in the specification is defined as a compound expressed by the general formula wherein Ac represents an acetyl group, and at least one of R R and R represents a saturated hydrocarbon group having from 11 to 19 carbon atoms, the rest being saturated hydrocarbon groups having one or from 11 to 19 carbon atoms.

The present invention characterizes as the filter elements use of commercially available cellulose material, i.e. viscose rayon fibers and crape paper. When viscose rayon fiber is used, an adhesive is applied to the bundle of fibers, and then the bundle is wrapped by paper to a cylindrical form. In the case of using paper, a sheet of crape paper is folded down to a cylindrical form and is enclosed in a wrapping paper. In this case, the adhesive may be applied directly to paper of the filter, but generally this is not necessary. Now, the filter elements of viscose rayon fiber will be described hereunder.

The viscose rayon fiber is preferably crimped fiber having a monofilament denier of one to 10. The fiber without crimps will give a filter which generally lacks elasticity and hardness required to cigarette filters. Therefore, the bundle of the fiber must have a large total denier. This increases suction resistance excessively, and tends to effect uneven filtration due to mutual sticking of the filaments. The amounts of crimps is preferably 8 to 25 crimps per 25 mm. When such crimped fibers are used as a filter element, the defects of the filters as above described will be precluded. Both the monofilament denier and total denier of fibers have influence upon the suction resistance, filterability, elasticity, hardness, and other properties of the resulting filter. In general, the less the monofilament denier or the more the total denier the greater the filterability; elasticity, and hardness of the filter will be. These advantages are offset concurrently with increase in the suction resistance, which renders smoking diflicult. The monofilament denier and the total denier should be adjusted according to some degrees on the crimp of the fiber and the amount of adhesive used, but generally the monofilament denier is desirable in the range of one to 10 denier, and the total denier of 40,000 to 100,000. A monofilament of 1.5 to 5 denier, and a total denier of 50,000 to 80,000 are most preferable.

These bundles of fibers are used in the form of continuous viscose rayon tows, or slivers obtained through preparatory processes of spinning such as mixing and scutching, carding, and drawing. In the case of tows, it is generally advisable to use those which are mechanically crimped, and in the case of staples, crimped staples are preferable. Since desired properties of a cigarette filter are the least possible suction resistance and uniform and great filtering capacity, the fibers to be used as a filter element should be paralleled substantially along the longitudinal direction and should be freed from small filament knots and other irregularities. Accordingly, it is important that tows should be thoroughly opened and loosened subsequent to the crimping treatment, and staples should be sufiiciently carded and paralleled to eliminate any unevenness of the total denier. Next, the use of paper as filter elements will be described. Paper as a material for cigarette filter elements should preferably be craped, and generally to be bulky. Craped paper can provide a filter which has adequate suction resistance and sufficient filtering capacity for tobacco smoke. Without crapes, the paper layers will fit closely to one another,

usually increasing the suction resistance excessively and bringing uneven filterability and hardness. When the paper is craped, the paper layers will contact with one another in a spot-like or linear fashion, so that smoke passages are maintained adequately, with practically no possibility of an execessive increase of suction resistance, or excessively large smoke passages which allow the smoke to pass unfiltered. Filters formed of paper filter element have a general advantage of large mechanical filtering capacity because of the complicate intermingling of the fibers, and the advantage is all the more enhanced by the use of bulky paper.

For improvement of filterability for tobacco smoke, hardness, and other properties of filters, and particularly for improvement of uniformity in quality of a filter, it is advisable to use not only bulky but also thin sheets.

To meet the technical requirements for jointing to cigarettes as well as the smokers requirements, cigarette filters must possess suitable elasticity, hardness, and dimensional stability, and it is therefore necessary in the case of viscose rayon fiber to compact the fibers suitably with adhesive.

The adhesive may be uniformly dispersed on the bundle of fibers in an amount equivalent to 2 to 30% of the total amount of the fibers, throughout the fiber mass thereby to cause su-rface adhesion of the filaments. Adhesion is preferably effected in a spot-like fashion at the contact points of filaments, in order that the filter can have a high filterability for tobacco smoke with a low suction resistance. The adhesive to be applied to the fibers may be within the range of 2 to 30% of the weight of the fibers for the filter elements for forming a cigarette filter, to prepare the filters suitable for practical use. With an amount of less than 2%, the adhesive cannot adequately attain the effects as such, for example the effects of improving the hardness of the filters and maintaining the dimensional stability, or improving the filterability of the product. Above 30%, it will cause local conglomeration of the fiber or an excessive increase of suction resistance. The most preferable amount of the adhesive is within the range of 3 to 15% of the total amount of fib r. Suitable adhesives for the invention are those whose solvents will not cause swelling of the fiber, and therefore watersoluble adhesives are usually not recommended. Suitable adhesives which can be usually employed include vinyl derivatives such as polyvinyl acetate, polyvinyl chloride, and polystyrene; acrylic acid polymers such as methyl polymethacrylate and methyl acrylate; polyolefins such as polyethylene and polybutadiene; polyamides; polyesters; copolymers of these compounds; and cellulose derivatives such as cellulose acetate.

The methods of applying adhesive on fiber include spraying of an adhesive solution over the fiber, dipping of the fiber in the adhesive solution, or forced introduction or application of the adhesive into a fiber tow by means of nozzles or rollers. It is further possible to sprinkle powdery adhesive Over the bundle of fibers, wrap the bundle with paper to a cylindrical form, and then to treat the filter with a solvent vapor thereby to dissolve the powdery adhesive.

When paper is used as filter elements, the filter can be kept hard by means of the rigidity of paper itself, so that an adhesive need not always be used in preparing the tobacco filter.

The addition of sugar esters to the filter elements which constitutes an important feature of the invention is intended to compensate the impairment of tobacco flavor and taste which has hitherto been an inevitable defect of cigarette filters made of cellulose materials, and also to permit highly efficient filtration for smoke constituents without affecting the balanced taste of tobacco. Irritant taste in tobacco smoke is attributed to a number of constituents, some reports say that basic and phenolic constituents in tobacco smoke are responsible. While the effects attained by the use of sugar esters in the present invention cannot be explained quantitatively and mechan- 4 ically, it is manifest from the examples given hereinbelow that the addition of the substance can improve the overall filtering capacity of the filter.

The sugar esters for use in the invention are substances of the general formula RICOOCHQ a lo\1-t a cooca o H H l V W AcO 2 5.

a A c 01w 1: 3

(wherein Ac represents an acetyl group, and at least one of R R and R is a saturated hydrocarbon group having from 11 to 19 carbon atoms, the rest being methyl groups). In practice, they include, for example, sucrose monostearyl heptaacetate, sucrose distearyl hexaacetate, sucrose monopalmityl heptaacetate, sucrose dipalmityl hexaacetate, sucrose monomyristyl heptaacetate, and sucrose dimyristyl hexaacetate.

These esters are invariably soluble in common organic solvents such as alcohols, ketones, and ethers, and are convenient in processing. As it is difficult to substitute all of the eight hydroxyl groups of sucrose into esters of higher fatty acids, and because it is believed unlikely that the substitution will remarkably enhance the effects to be attained, only one to three hydroxyl groups of sucrose may be susbtituted with higher fatty acid esters. It is advisable to esterify the hydroxyl groups of sucrose, in point of handling and effects thereby attained. Furthermore, much of the effects described above cannot be expected of the sugar esters unless they contain esters of higher saturated fatty acids.

Higher fatty acids, when unsaturated, give disagreeable smells or may color the filter material, and are hence not recommended. Such fatty acids whose alkyl group has 11 to 19 carbon atoms are highly effective and are, moreover, generally available. The addition of the sugar esters to filter material may be conveniently effected by applying the esters in the form of solutions in organic solvents. The methods of adding the esters may include, in the case of a paper filter material, spraying of the sugar ester solution, or dipping of paper in the solution, and in the case of fiber, mixing the sugar esters in the adhesive solution, or application of the sugar ester solution to the filter elements in the same manner as in the case of paper filters. The amount of sugar esters to be added to the filter material is satisfactory if in the range of 0.05 to 10% of the weight of the fibers or the paper for the filter elements. At less than 0.05%, the additive will not prove sufficiently effective, and over 10%, it will give rather unfavorable effect of the hardness and other properties of the resulting filter, and thus a corresponding increase in the favorable effect cannot be expected. Industrially, the most desirable range for the addition of sugar esters is from 0.1 to 5%.

The sugar esters according to the invention can have appreciable effects when added even in very small amounts to filter elements. They are almost odorless, colorless, and are non-toxic, and the use of these additives will not adversely affect the mechanical and other properties of cigarette filters. Furthermore, most of the sugar esters to be used in the invention have melting points in the range of 10 to 40 C., and hence, once applied to filter material, they will not split off the base. As will be readily understood by those skilled in the art from the methods of application above described, the sugar esters are applied in such state that the fibers of cigarette filters are substantially uniformly impregnated or coated with the esters, without danger of partial unevenness of filterability. Moreover, the adidtives will not increase suction resistance of filters excessively, because they are not powdery. The filter materials treated as hereinabove described are enclosed in a wrapping paper and formed to a columnar shape of a desired diameter, in the usual manner, tor exmple by a cigarette machine of the conventional type.

Example 1 Viscose rayon staple fibers having a monofilament denier of 3, and 16 crimps per 25 mm., and a staple length of 76 mm., were paralleled through the stages of scutching and carding similar to ordinary spinning processes, to form a sliver, 65,000 deniers in total denier size. The sliver was dipped in a methanol solution containing 8% of polyvinyl acetate (PVAc), and 0.5% of saccharose distearyl hexaacetate (SDSA), squeezed by rollers at a squeeze rate of 200% (additive amount: PVAc 8% and SDSA 0.5%), and passed through a pre-drying furnace (a hot blast circulating furnace at 80 C.) thereby to evaporate the solvent to such an extent that the residual amount of solvent was about The filter fiber thus treated was then fed into a wrapping machine, and was formed to a continuous roll circular in cross section and having a circumference of 24.7 mm. enclosed in wrapping paper. The roll was cut into pieces, each 102 mm. in length, to form cigarette filter plugs. Further, the plugs were cut to lengths of 17 mm., and assembled to cigarettes in order to produce filter cigarettes.

As a control, the same sliver as above was treated with a methanol solution containing 8% of polyvinyl acetate but not saccharose distearyl hexaacetate, and filter plugs were formed of the treated sliver, and were cut to pieces of 17 mm. long, and fitted to cigarettes, by following the same procedure as above. The filter thus obtained was used as control 1-1. Separately, a commercially available filter formed of a cellulose acetate fiber having a monofilament denier of 4 and a total denier of 70,000, with the addition of a plasticizer, was used as control 1-2. The results of performance tests conducted on these test pieces are given in Table 1. When cigarettes fitted with the three types of filters were smoked, control 1-2 gave a disagreeable irritating taste, while the filters of Example 1 and control 1-2 were not irritative.

TABLE 1 Pressure Percent Percent o nicotine tars (mm. 1120 Hardness removal removal Example 1 300 8. 6 34. 2 38. 3 Control 11 310 8. 7 30. 9 33. 4 Control 1-2. 282 7. 5 32. 7 34. 1

In the above table, the pressure drop and hardness values are those determined of 102 mm.-long filter plugs. In testing the specimens for pressure drop, the plugs were aerated at a rate of 20 cc. per second, and the resulting pressure drops were determined in terms of water column heights. The hardness values were obtained by applying a load of 300 g. to a side of each filter plug with a disc,

' 12 mm. in diameter, and then determining the resulting Example 2 A viscose rayon tow having a monofilameut denier of 4 and a total denier of 70,000 was crimped by a crimping machine thereby to have 19 crimps per mm. (in terms of residual crimps after opening). Next, the tow was loosened by alternate tension and relaxation, and was thoroughly opened in an opening machine equipped with a porcupine roller for an enhanced opening efiect. An acetone solution containing 2.5% of cellulose acetate (CA) and 0.3% of saccharose dipalmityl hexaacetate (SDPA) was sprayed on the circumference of the fiber bundle by means of four spray guns. Immediately thereafter, the fiber mass was squeezed with rollers, to a residual solution content of 14.0%.

From the stock was preliminarily dried, papered, formed to filter roll, and cut into filter plugs, in the same manner as described in Example 1. The amounts of CA and SDPA deposited on the fiber were about 3.5% and about 0.4%, respectively of the total amount of the fiber. The filter properties were: pressure drop, 295 mm. H O; hardness, 7.7; percent nicotine removal, 33.8%; percent tars removal, 37.4%.

Example 3 A sheet of bulky paper craped in the lateral direction, in the form of a continuous strip weighing about 20 grams per square meter but 50 cm. in width, was passed through a bath containing a 0.5% ethanol solution of sucrose distearyl hexaacetate, squeezed by rollers at a squeeze rate of 200%, led through a hot blast oven kept at C., and fed into a wrapping machine. In the machine, the sheet was grooved in the longitudinal direction by means of grooved guides, folded to a width of 3 mm., enclosed in a belt, and forced through a cylindrical nozzle to a columnar shape. The periphery of the column was further enclosed in wrapping paper and sized to a continuous rod-like shape. The filter thus formed was cut to lengths of 102 mm. thereb to form filter plugs. In fitting the plugs to cigarettes, the 102 mm.-long plugs were further cut into 6 pieces of equal lengths. As control 3-1, paper not treated with sucrose distearyl hexaacetate was formed in the same manner as above. These filters were tested for the performance, the results being as given in the following Table 2.

In the above table, the pressure drop and hardness values are those determined of 102 mm.-long filter plugs. In testing the specimens for suction resistance, the plugs were aerated at a rate of 20 cc. per second, and the resulting pressure drops were determined in terms of water column heights. The hardness values were obtained by applying a load of 300 g. to a side of each filter plug with a disc, 12 mm. in diameter, and then determining the resulting depths of dents on the filter plugs, in fractions of a millimeter. The less the numerical values, the harder the filter. In tests for percent nicotine and tars removal, 17 mm.-long filters were fitted to cigarettes, and intermittent pufiing was performed by an artificial smoking apparatus. The nicotine and tars contents of the smoke and filtrate were determined by the ultraviolet ray absorption spectrum method for the nicotine content and by the chloroform-extraction colorimetry for the tar content. On the basis of the values so determined, the percent nicotine and tar removal was calculated, respectively.

Example 4 Over a sheet of bulky paper craped in the longitudinal direction, weighing 17 grams per square meter and 60 cm. in width, a methanol solution containing 1.5% of sucrose monopalmityl heptaacetate and 2% of polyvinyl acetate was sprayed from both sides of the paper, by means of spray guns, so that the solution applied to the paper amounted to 80% of the paper amount. The coated paper was then passed through a hot blast stove kept at 50 C. thereby to evaporate the methanol, and further into a spiral nozzle, and was rolled with a cigarette paper to a columnar form. Next, the column was cut to filter plugs, each 102 mm. in length. The plugs thus obtained had the following properties: pressure drop, 326 mm. H O; hardn coocn 3 a a coocrr Q 3 o H A60 CHQOOCRB] AcO a on on 3 wherein Ac represents an acetyl group, and at least one of R R and R is a saturated hydrocarbon group having from 11 to 19 carbon atoms, the rest being methyl groups, in an amount ranging from 0.05 to 10% by weight of the total amount of the filter material.

2. The cigarette filter according to claim 1, wherein said sugar ester is selected from the group consisting of sucrose monostearyl heptaacetate, sucrose distearyl hexaacetate, sucrose monopalmityl heptaacetate, sucrose dipalmityl hexaacetate and sucrose dimyristyl hexaacetate. 3. A cigarette filter according to claim 2, wherein the sugar ester is sucrose monostearyl heptaacetate.

4. A cigarette filter according to claim 2, wherein the 5 sugar ester is sucrose distearyl hexaacetate.

5. A cigarette filter according to claim 2, wherein the sugar ester is sucrose monopalmityl heptaacetate.

6. A cigarette filter according to claim 2, wherein the sugar ester is sucrose dipalmityl hexaacetate.

7. A cigarette filter according to claim 2, wherein the sugar ester is sucrose dimyristyl hexaacetate.

References Cited UNITED STATES PATENTS 2,228,383 1/1941 Berl 131268 3,008,474 4/1959 Touey et al l3l266 3,344,796 10/1967 Yamaji et al. 131-267 20 SAMUEL KOREN, Primary Examiner.

D. I. DONOHUE, Assistant Examiner. 

